The first sentence of the Wikipedia article on Social Responsibility:
Social responsibility is an ethical framework
To answer your questions:
is ethical design inclusive of socially responsible design practices
If one’s practice includes concepts of ‘ethical design’ then I’d assume ‘social responsible’ design would be considered part of that ethical mantra. So, yes, in that sense it’d be inclusive of all aspects of ethical design.
are they different considerations when it comes to product/service design in the digital space
I don’t see how something being digital would change any sort of ethical standards regarding the design process.